HELP

Can't remember the title, please help! MC is a florist, who used to be a gangster or high up in the yakuza. The only reason he is able to safely transition to working as a florist and living peacefully is because the ML is making the city safe for him to do so in secret. MC has no idea ML is jumping though hoops in the shadows to keep his peaceful lifestyle going. I think it is a black and white manga but I can't remember. Thank youuu